Dental restorative systems seek to provide cosmetic and functional replacements for missing teeth. Typically, methods for tooth replacement involve placement of an anchor, called a dental fixture, in the patient's jaw. The dental fixture is inserted into a hole drilled into the jaw. It provides a receptacle for the replacement tooth. Prior to replacement, however, an impression of the local dentition must be taken. The impression should preserve features of the dentition, including the position and alignment of the site for tooth replacement. An integral feature of this process is the use of an impression coping device, which serves to orient and preserve the impression of the local dentition. This allows a technician to form a replacement tooth that matches the contour and orientation of the natural teeth. The impression coping device typically is placed into the bore of the dental fixture, described above. In dental restorative systems of the art, a screw or bolt is used to anchor the impression coping device in the dental fixture. Once the impression coping device is screwed into the dental fixture, an impression of the local dentition can be taken.
Proper orientation of a replacement tooth is important both cosmetically and functionally. The impression coping device aids in this process by providing a substrate for an impression of the area in which tooth replacement will occur. The impression is formed around the impression coping device in a patient's mouth. The impression coping device and the attached impression are then removed from the patient's mouth, and are used as a basis for construction and orientation of a replacement tooth by a dental technician.
Typically, a screw assembly is used to secure an impression coping device to an implanted dental fixture. A dental fixture, therefore, generally consists of a central bore with screw threads for receiving a screw. The exposed surface (i.e., the surface of the fixture protruding from bone) of an implanted dental fixture typically consists of a hexagonal or round interface for defining the orientation of attachment of a tooth analog. An impression coping device is attached to the dental fixture by a screw that threads through the coping and into a central bore of the fixture. The screw mates with threads in the fixture in order to secure the impression coping. An impression of the dentition surrounding the tooth to be replaced is then taken. The impression then is removed from the mouth and used to fabricate a tooth analog, as indicated above.
In order to obtain a proper fit of the tooth analog, it is desirable to maintain rotational alignment between the implanted fixture and the patient's natural dentition. This requires that the impression coping device engage the implanted fixture in a non-rotational manner. Screw mechanisms used to secure impression copings tend to interfere with the rotational alignment of the impression.
Difficulties in handling and properly installing screws or bolts to secure coping devices have lead to improvements, such as an interlocking coping device comprising a screw that is non-removably inserted through the central bore, thus allowing insertion of the coping device and the screw in one step.
There remains, however, a need in the art for impression coping devices that are quicker and easier to use, and that resist rotational and other influences that cause misalignment of new tooth implants.